Didn't hear any update from you. Hopefully your cat already spayed.

on purpose? i kena once cause cat standing inside box but crap outside of the box.... tak perasan kot...

the ass jutt outside box kot... try bigger box or box wit high walls..

wht type litter ? pine pellet? i think cat likes clay litter the best, the softer it feels, almost like fine sand, more the cat likes..

Maybe fighting and don't wanna share? Do you specify which box for each cat? or share share until fight and tunjuk perangai...

How old is your cat?

Usually there are many reasons why cats behaving like this for example picky (if there's already poo in the litter box), upset stomach (they feel uncomfortable when pooping and associate that feeling when pooping in the litter box which means sometime they avoid using litter box because of that reason), health issue and many more.

You can try pickup your cat's poop from the litter box more frequently. You can try use different clay litter. You mentioned using clay litter but are they clumping or non-clumping? If non-clumping, change to clumping type. If you have a cage, try cage your cat with a litter box in it. For example caging your cat at night for a couple of days and then see whether this improved your cat behavior. If your cat still poop outside litter box in the cage, you should bring your cat to vet.

IMO, this sound like your cat misbehave than health issue though. Good luck.

street cat? breed?

if just normal cat, then just get whiskas pouches.